Regulating mechanism for valves



y 1943 G. MCCULLOUGH 2,319,335

REGULATING MECHANISM FOR VALVES Filed Aug. 22, 1941 INVENTOR GERALD MCCULLOUGH Patented May 18, 1943 A a f 2,319,336

aaovulrmq MECHANISM FOR. vALy Gerald W. McCullough, Bartlesville, ;kla., as-

signer to Phillips Petroleum Company, a corporation 01' Delaware v 7 f This invention relates to improvements in a pneumatic shittcontrol cylinder and valve stem travel stop aclJustment mechanism for, motor J valves. The motor valves for which my improve-,

ment'is especially adapted, are those operating under high pressure; for example, pressures of the order up to 5,000pounds' or even as high as 10,000 pounds per square inch, and at temperatures up to 1,000? or higher, yet my improve! ment is equally "well adapted for use with lower pressure valves; v

In manufacturing, refinery or gasoline plant operation, there are many applicationsflinvolving pressure. temperature and flow controlsfwhich require the installation of the control valve; commonly called a motor valve, adjacent to the apparatuspr at some intermediate pointof a process and at a point usually remote from the operator's 'controlroom. Such applications require manual' or gear operated mechanisms directly connected to the valve stem. lncomplexoperating processes, it is rarely-possibleto'set axcontrol valve in a nxed position "without, limiting the flexibility and efllciency or the process. For this reason it has become most'des'irablekto use an i V .25 automatic resetting-control 'to actuate hydrauli- J 'cally or pneumatically the diaphragm head of the control valve, as in conventional motor -valves.-

I In ordinary commercial operations motor valves are not equipped with facilities to allow either \manual or automatic actuation, or both,

' to .permit precise positioning or provide for con-' siderable travel limits of the inner valve "stem.

Such flexibility-is required it the valve is to be able to be used for manual or automatic operation, each independent" of the other. 1

In processes in which the-location of the con trol valve is such as to'be exposed to occasional or-possible fires, it becomes notonly desirable but necessary to provide, in addition to the automatically controlled" diaphragm 3 motor valve, mechanism for manually setting or adjusting the position of the inner valve of the motor or control valve without requiring the presence'oi the:

operator in hazardous areas, that is, the operator may make the adjustments from a remote point, .as i'or'example, in a remotely located control house.

- Motor valves equipped with such settingor adjusting mechanisms'permit positive movement of the inner control valve; By this valve movement against the valve port insert seat during passage of'high pressure fluid through the valve,

the velocity of the fluid passing under force of "Application Auxust 22, 1941, Serial No; 407,965 a 15Claims; (Cl. 137-139) V per square inch cleans and removes all coke, or

decokes the .valve seat. I, h

, "An object ot'this invention is to provide a normally Iautomatically operable motor valve, which maybe manually'operated from a remote distance. 1 'Another object of :this invention is to provide an automatically operable motor valve, the limits of valve operations of which maybe manually jcontrolled or set from a remote distance. Still another object of this invention is to provide an automatically operable motor valve for high pressure and hi'gh' temperature service, with provision for cleaning or decoking the valve seat and innervalve'surface' while the valve is operation, the cleaning or decoking mechanism being operated at a distance remote from theljvalve,

thereby not requiring the operators going into i the hazardous furnace area. I

a further object is'the provision of a means for setting the range of movement of a valve and also for setting theposition of, said range ofvalvemovement' between upper and lower limits;

These and otherobjectsand advantages will ,be realized bythose skilled in the art from a I,

carefulstudy of the following disclosure.

Figure 1 represents a high pressure motor valve withmy improved manually or automatically operated controls thereon; partly in elevation and partly in, section. 1

Figure 2 shows the trunnion blocks employed {in the apparatus of Figure 1 with attached dog- Figure 3 showsan'auxiliary view of the convFigure 4 shows the valve travel indicator. Like numerals refer to like members and parts .of the apparatus represented in the several drawings.

Referring to the figures, numeral I0 represents the valve, body of a high pressure, high tempera ture motor valve. This type of valve body is ordinarily equipped with stellite body liner, outlet liner, valve port insert, locking rings and guide bushing'as standard equipment. The inner valve II also has a stellite surface. The finned bonnet I 2 is" commonlyused on process applications in which high temperature material is passing through the valve; A spring barrel l3 of the enclosed type is shown, with interior springs, not shown, which are intended to hold the inner valve ll 'ofi the seat in case the automatic motor valve diaphragm actuating pressure should fail.

such pressures as 5,000 to 10,000 pounds pressure The diaphragmhead I4 is equipped w t a trol screw levers and shaft assembly of Figure 1.,

ventional diaphragm, and a top connection for attachment to the actuating hydraulic or pneu-' matic pressure source. This actuating pressure acting on the diaphragm tends to compress the springs and hold the inner valve H on its seat,

and hence the valve closed to the passage of fluid.

In case of failure of the actuating pressure, as mentioned above, the barrel springs exert their pressure and raise the diaphragm, thereby openof my improved apparatus comprises a pressure cylinder 46 with actuating air supply connections 4-; and 45 into the ends thereof. The pressure cylinder 46 contains a piston l6 which in turn is connected to piston rod l6, to clevis 68, to link l1, and to shifting yoke l6. This shifting yoke is anchored to the control housing 65 by means of clevis 69, clevis rod 46 and flange 4|. The shifting yoke l6 and spline shaft 26 are connected flexibly by the moving shift collar assembly Is. To the inner end of spline shaft 26 is attached the .clutch yoke 2 outerend of spline shaft 26 and spline sleeve 22 lby conventional means. The

are of sufficient length and overlapping that the small movement of spline shaft 26 will not interfere with the manual rotation of the universal joint 26, the spline sleeve 22, the spline shaft 26,- clutch yoke 2| and central clutch member 66. The central clutch member 66 engages either the outer clutch plate 24 or the inner clutch plate 26 or it may be positioned in a neutral position-engaging neither clutch plate.

Extending from beyond outer clutch plate 24 into and through the manual control housing 66 is the control shaft 46.. The outer clutch plate 24 is fixed rigidly to the control shaft 46 by essentially any suitable means, as for example, bolt 66 and nut 66, so that'upon rotation of clutch plate 24 the entire control shaft 46 rotates.

Within the manual control housing "said control shaft 46 carries two movable trunnion blocks 26 which move in opposite directions on shaft 46 upon rotation of said shaft due to bein threaded with opposite handed threads. Thus upon rotation of shaft 46,

said trunnion blocks 26 move toward or become further separated from one another depending upon the direction of rotation of the shaft. The blocks travel longitudinally with respect to the axis of the shaft since the dogears 66 are held in position by the control screw levers 21 and 26 and thereby prevent rotation of the trunnion blocks with the control shaft 46. Ball bearing 62 supports the inner end of control shaft 46. t

The inner clutch plate is attached to the control screw 34 by any convenient means, as for example, two small bolts 64, one visible in the front circumference of inner clutch plate 26 and the other 180 degrees around and on the back circumference of said clutch plate. This control stem connector 66 screw 34 carries external threads which mesh with internal threads of support-42, the latter being an integral part of the manual control housing 66. The said control screw is connected to control shaft by ball bearings 48 and 56. Into the inner end of the control screw 64 is fitted ball p ace y he bearing 56 which latter is held in a by key 61 or shoulder 6| on one side and by the control shaft thrust collar .46 on the other side. Said thrust collar 46 is rigidly attached means to the control shaft 46. Y

The ball bearing 46 is held in place in a manner similar to that described for bearing 66, that is by shoulder 62 and clutch thrust collar 41.

From this control shaft assembly as shown in Figure 1 and above described, it is obvious that the two clutch plates 24 and 26 are held apart by clutch thrust collar 41 and control screw 64 is fixed with respect to longitudinal movement along control shaft 46 by bearings 46 and 66 which are held in place respectively by collars 41 and 46.

The central clutch member 66 is free to rotate around clutch thrust collar 41 and also is free to move longitudinally thereon.

Thus by rotation of outer clutch plate 24, the trunnion blocks 26 move to become more or less widely separated from one another, depending upon the direction of rotation, and by rotation of the inner clutch plate 26, the entire control shaft 46 control screw 64 assembly moves further into or. out of the control housing 66 depending upon the direction of rotation. when this latter movement takes place,.the trunnion blocks and dogears do not move with respect to one another and they are maintained the same distance apart. when control screw 64 is of the yoke control screw levers 21 and 26 with. respect to the trunnion block dogears 46 prevents the rotation of the control shaft 46 and thereby causes the proper longitudinal movement of the control assembly.

The movement of the yoke control screw lever 21 moves the upper yoke travel stop lever 26 since both are an integral casting and mounted on a common hollow shaft 64, see Figure 3. This common shaft 64 is hollow and fitted to rotate atleast through a small angle on shaft 66. The shaft 66 is attached to the inner wall of the control housing 66 by the bearing supports 66.

The yoke control screw lever 26 is fixed rigidly by other means to shaft 66 as is the lower travel stop lever 66 to prevent rotation of these levers on shaft 66. Shaft 66 is held in place longitudinallyby collars "carrying set screws 66; Thus when trunnion blocks 26 oncontrol shaft 46 move, the upper and lower travel stop levers 26 and 66, respectively, move also.

position along the valve stops 62 is determined by the position of the upper and lower travel stop levers 26 and 66.

- These trunnion stops 62 are equipped with dogears similar to those on trunnion blocks 26. The valve stem 6| carries a rigidly fixed valve upper and lower trunnion stops 62.

To the upper. and lower trunnion steps 62 are connected upper and lower 66, as-shown in Figures stop pointers indicate on the valve travel indi-' cator 6| the manually set limits of travel of the valve stem 6|. Tothe valve stem connector 66 is atached a valve stem travel pointer 61 as shown also in Figures 1 and 4. This pointer indicates also on valve travel indicator 6| the position of the valve stem at any time with respect to the manually et limits of travel, the former being indicated by the travel pointer 61 and the latter by the travel stop pointers 66.

Air connections 44 and 46 are connected by means of piping to an air supply which is regulated from the control house. Similarly the unitravel stop pointers by any conventional turned. the 7 position a stem 6| of trunnion which is locatedbetween the 1 and 4. These travel .therebyopeningvalvelL. v 1

(c) The .valve may be partially opened and versal joint 23 is connected by a series of shafts,

plain and/or bevel gears and other necessary conn'ecting apparatus, not shown, to a control wheel inthej above mentioned control-house so that the operator may by manually rotating this, control wheel rotate the control shaft 46 or the control 1 screw 33, thereby setting the travel limits of the motorvalve steniiil, Y Y.

Thevalve' travel indicator} I shown. in Figure l 4 should, preferably be connected to a recordingapparatus, of any suitable design whichapparatus is then mounted in the above mentioned control house so that the entireinspection, adjustments an operation of the automatic motor valve may be made therefrom In the operation of this manual or automatic control. the-valve may be held (a) closed, (b) fully open or at any (clintermediate point. Inaddition, (dHo'wer-and upper limits for automatic operation may be adjusted motor valve, by, remote n per andlower trunnion stops 32- arelikewi'se moved closer toward one another until they both touchand hold firmly the valve. stemconnector 33. Then by admitting control air into air inlet "46 and operating the remotely located manual I controlmechanism, as described above, for tumingcontrol screw" the valve H may beentirely closed,- entirely opened or maintained in any intermediate position; Under these conditions the valveis not free to operate automatically from the diaphragm head I.

the proper spacing of the trunnion stops 33 as '(d') For automatic operation between limits for partially opening and partially closing the motor valvefthese limits may be set and maintained by my manual remote control mechanism. Thus by controlled by rotation of the control shaft 36, and

and maintained. from a remotely located control mechanism permitting automatic operation between these s'et'li'mits.

j [(d) To close'the valve,completely,the oper-' atoradmits' air into air line "from a'z'emotelv located control room, piston l imoves' from left v toiright according torepres e'ntation in Figure 11, -thereby"causing central clutch member .63 to mesh withinner clutch plate 26. The operator then by a remotely located manualgrevolving mechanisnn.

by the location of these trunnion stops 32 with respect to-the-valve stem connector 33 as controlled "by rotationofthe control screw 33 and by the setting ofthe said valve stem connector on the valve stem 3|, automatic operation as connotshown, turnsuniversal vjoint-33 and-by.con-. I I

. necting parts controlcscrew- 34 is turned in the direction, according to the-threads on, saidcontrollscrew, so that the control screw 33, carrying the control ,"shaft 36, with trunnionblocks and dogears 26 moves from, right to left; in Figure 1, thereby causingupper travel stop lever 23 to move upper trunnion stop 32 in a downward direction.

in" the neutral trolled from the diaphragm head l3 maybe accomplished; For the automatic operation it is preferable'to maintain central clutch member 63 position and not either clutch plate ll or ii. U

The tension of the barrelsprings within spring barrel i3 is intended to besuch that if the actuating hydraulic or pneumatic pressure operating the diaphragm head i3 should-fail, the valve will be raised by said spring to the upper set travel limit, thereby. not forcing closing down of the rocess. :Should this condition occur, th 'valve may then bemanually oontrolledand operated as Whenthis'trunnion stop contacts valve stem ,con-

'nector 33 which is attached rigidlylto the valve' stem 3 I the valve stem and valve are moved downward and this movement llisclo'sed with respect to itsseat.

( b) Toopen the valve, air is admitted into inner clutch i t lzs. Then from the remotely located manual control, the control screw 34; is V rotatedlin the rcverse-direction from that given continued until valve.

u; as above given, forcing. piston i 6 from left to right causingcentrai clutch member 63 to mesh with:

. aboveunder (a) and thecontrol screw 33- -control shaft 46 assembly travels from left to right and in so doing the left trunnion v =block moves to cause the lower trunnion stop 32 to be moved iipwardly until it contacts valve stem connector .33.? Upon continued upward. movement :of said lower trunnion stop 32the valve stem 3| is raised maintained in that positionduring manually con.

trolled refining or. manufacturing operations. From the aforementioned; remotely located conheretofore explained. 5

When a valve is insertedin high temperature refining process such as thermal alkylation, polymerization and cracking, it frequently happens that valves are clogged by coke deposits. One advantage-army invention resides in the fact that whenv operating at high pressures such as 5,000 or l0,000 pounds per square inch coke deposits may be removed'from said valveswithout' interrupting operations; This "decoking," step I may becarried out by lowering the valve stem 3| 1 and valve lljas hereinbefore disclosed until the valve is just barely open. Under this condition.

the very high velocity of the fluid passing under force of such pressures as 5,000 or 10,000 pounds is completed, the valvetravel stopsare' reset and the valve put back on, automatic operation.

per square inch cleans and removes all coke from the valve and its seat without disrupting operation. After'tlie cleaning or decoking operation It is not intended to limit my invention to the particular design'as shown since many modiflca trols, air i admitted through air connection, thereby causing. piston ,l6 to movefrom right to left according to the drawing. This piston ,move-. vmerit causes central clutch member- 33 to mesh with .the outer clutch plate 24. Then from the remotely located controls, not shown,the operator turns universal joint 23, the rotation being carried by connecting parts to the centralclutch member '53., In this position the-revolving central clutch member 63 revolves thev outer clutch plate 24- which in turn revolves control shaft 36, thereby. moving trunnionblocks ,2 6'. The direction of rota-.

tion of said control shaft is such and depends on the directions .of "threading on theshaft, as to 75 tions and variations may be made and yet remain within the intended spirit and scope of my invention. I 1

Materials for construction ofparts may be.

seiectedfrom those best suited for the purpose.

I claim: I

, 1. In a motor valvemechanism including 'a valve casing,-a valve'movable between upper and lower limits in said casing and a valve stem,

' means for setting intermediate range of valve travel comprising a control-shaft having oppositely threaded sections, members. threaded to the control-shaft on said sections and movable in opposite directions thereon by relative rotation of said shaft, 'a' stop for said valve stem,

pivoted levers having corresponding ends movmove the trunnion blocks 26 closer together.: By continuing the-rotation of control shaft 36, the

meshing with levers being movable adjustably along said valve stem and limiting the movement thereof by means of said stop and means for communicating rotation to said control shaft.

2. In a motor valve mechanism including a valve casing, a valve movable between upper and lower limits in said casing and a valve stem,

means for setting intermediate range of valve travel comprising a. control shaft having oppositely threaded sections, members threaded to the control shaft on said sections and movable in opposite directions thereon by relative rotation of said shaft, a stop for said valve stem, pivoted levers having corresponding .means for setting intermediate limits for the range of valve movement including a control mechanism including a shaft having oppositely threaded sections, members threaded to the control shaft on said sections and movable in opposite directions thereon by relative rotation of said shaft, a stop for said valve stem, pivoted levers having corresponding ends movable by said members, the opposite ends of said levers being movable adjustably along said valve stem and limiting the movement-thereof by means of said stop, and means for setting thev relative positionof the range of valve movement between said upper and lower limits.

4. In a motor valve mechanism including a valve casing, avvalve movable between upper and lower limits in said casing and a valve stem, means for setting intermediate limits for the range of valve movement including a control shaft having oppositely threaded sections, members threaded tothe control shaft on said sections and movable in opposite directions thereon by relative rotationof said shaft, a stop for said valve stem, pivoted leversehaving corresponding ends movable by said members, the opposite ends of said levers being movable adiustably along said valve stem and limiting the movement thereof by means of said "stop, and means imparting endwise movement to said control shaft for setting the relative position of the range of valve movement.

5. In a motor valve mechanism including a valve casing: a valve movable between upper and lower limits in said casing and a valve stem, means for setting intermediate limits for the range, ofvalve movement including a housing, a

control shaft having oppositely threaded sections, members threaded to the control shaft on said sections and movable in opposite directions thereon by relative rotation of said shaft, a stopfor said valve stem, pivoted levers having corresponding ends movable by said members, the opposite ends of said-levers being movable adable by said members, the opposite ends of said endwisemovement to said shaft, an inner clutch plate fixed to said control screw, an outer clutch plate fixed to said control shaft, and an inter- I mediate .clutch member for selectively operating said inner and outer clutch plates.

6. In a motor valve mechanism including a valvecasing, a valve movable between upper and lower limits in said casing and a valve stem, means for setting intermediate limits of valve movement comprising means for setting intermediate limits for the range of valve movement including a housing, a control shaft lnvingopmsitely threaded sections, members threaded to the control shaft on said sections and movable in opposite directions thereon by relative rota tion of said shaft, 9. stop for said valve stem, pivoted levers having corresponding ends movable by said members, theopposlte ends of said levers being movable adiustably along said valve stem and limiting the movement thereof .by. means of said stop, an outer clutch plate communicating rotation to saidcontrol shaft to, set the intermediate limits for the range of valve movement, and means for setting the relative position of the range of valve movement includ ing a hollow control screw exteriorly threaded to said housing and receiving said control shaft in a longitudinally fixed relation, rotation of said control screw imparting'endwise movement to said shaft, an inner clutch plate fixed to said control screw, and an intermediate clutch member for selectively operating the outer clutch plate to cause the opposite ends of said pivoted levers to flxe the intermediate ,limits of "range of travel of the valve and for selectively operating the inner clutch plate to impart endwise movement to said control shaft to fix of the range of valve movement.

, 7. In a valve mechanism including a valve casing, fluid inlet and outlet passages for said casing, a-valve movable between upper andlower limits in said casing and a valve stem, means for setting intermediate valvetravel limits comprising a control shaft, a stop for said valve sfem, pivoted control levers, means associated with said control shaft on rotation thereof to impart oppothe position site movement tov corresponding ends of said levers, the other ends of said levers being movable adiustably'along said valve stem and limiting the movement thereof by means of said stop and means for communicating rotation to said control shaft.

8.'In a valve mechanism including a valve casing, fluid inlet and outlet passages for said casing, a valve movable between upper and lower limits in said casing and ,a' valvestem, means for settingintermediate limits determining the range of movement for said valve comprising a control shaft, pivoted control levers, means associated with said control shaft on rotation thereof justably along said valve stem and limiting the movement thereof by means of said stop, means for setting the relative position of the range of valve movement between said upper and lower limits including a hollow control screw exteriorly threaded to said housing and receiving said control shaft in a longitudinally fixed relatlon, rotation of said control screw imparting to impart movement to corresponding ends of i said levers in opposite directions, a stop for said valve stem, the opposite ends of said leversbeing .movable'adjustably along said-valve stem and limiting "the movement thereof by means ofsald stop, means for communicating rotation to said control shaft to set the range'of movement for said valve and means for imparting endwise movement to said control shaft to locate the relative position of the range for valve movement between'said upper and lower limits.

9. In a valve mechanism 'includinga valve casing, fluid inlet and outlet passages for said casing, a valve movable between upper and lower limits in said casing and a valve stem, means for setting intermediate limits determining the range of movement for said valve comprising a control shaft, pivoted control lev'ers' for said control shaft, means associated with said control shaft imparting movement to corresponding ends of said levers in opposite directions on rotation of said control shaft, a stop for said valve stem, the opposite ends of said levers being movable adjustabl-y along said valve stem and limiting the movement thereof by means of said stop, means for imparting endwise movement to said control" shaft thereby determining the relative position of the range for valve movement between said upper and lower limits, and controlmeans for selectively setting intermediatelimits for the range of valve movement and setting the range between said upper and lower limits. I

10, A control mechanism for motor valves including a valve casing, fluid inlet and outlet passages for said casing, a valve movable'between upper and lower limits in said casing and a valve stem, means for setting intermediate .limits for the movement of said valve comprising a stop for said valve stem, a housing, a control shaft joumaled in said housing at one end, a hollow control screw-exteriorly threaded to said housing and receiving an opposite section of said control shaft for imparting endwise movement thereto, oppositely, threaded sections on said control shaft, members threaded to the control shafton said sections and movable in opposite directions thereon by relative rotation of said shaft, a pivot shaft mounted insaid housing, levers pivoted on said shaft having corresponding ends movable by said members, the opposite. ends of said levers being movable adjustably along said valve stem and limiting the movement thereof by means of said stop, and clutch means selectively imparting rotation to saidcontrol'shaft to determine the magnitude of movement of said valve bearing for the opposite end -of said control shaft but preventing longitudinal movement thereof relative to the control screw, whereby endwise movement is imparted to said control shaft by relative rotation of the control screw, control levers pivoted in said housing, means associated with the control shaft imparting movement to corresponding ends of said levers in opposite directions, a stop on said valve stem, the oppo-i site ends of said levers being movable adjustably along said valve stem and limiting the movement thereofby means of said stop, and clutch means for selecting rotation of said control screw and said control shaft, said means being remotely controlled by fluid pressure. p

13. Ina valve mechanism including a valve casing, a valve movable between upper and lower limits in said casing and a valve stem, means for fixing rigidly the position of the valve between v said upper and lower limits comprising a housing,

. a hollow control screw exteriorly threaded to said housing, a control shaft, a bearing in said housing for one end of'the control shaft and permitting endwise movement thereof, the inte'rior of the control screw forming a bearing for the opposite end. of said control shaft, said control shaft being fixed against longitudinal movement relative to said control screw, lever means and rotating said control screw thereby imparting endwise movement to said shaft and deter- Y mining the relative position for said range of valve movement.

11. A control mechanism for motor valves including a valve casing,-fluid inlet and outlet passages for said casing, a valve movable between upper and lower limits in said casing and a valve stem, means for setting intermediate limits for the movement of said valve comprising a nousing, a control shaft, a bearing in the housing supporting one end of the control shaft and permitting endwise movement thereof, a hollow control screw exteriorly threaded to said hous ing, the interior of said control screw forming a bearing for the opposite end of said control shaft but preventing longitudinal movement thereof relative to the control screw, whereby endwise movement is imparted to said control shaft by relative rotation of the control screw, control "60 levers pivoted in said housing, means associated with the control shaft imparting movement to corresponding ends of. said levers in opposite directions, a stop on said valve stem, theoppositev ends of said levers being movable adiustably along said valve stem and limiting the movement thereof by means of saidstop, and control means selectively setting intermediate limits forthe range or movement of said valve and fixing the I range of valve .movement'between said upper and lower limits.

pivoted in said housing, one end ofwhichbeing connected to said control shaft, and the opposite end connected to said valve stem whereby the position of said valve is determined by relative rotation of said control screw.

'14. In a motor valve mechanism including a valve casing, a valve movable between upper and lowerlimits in said casing and a valve stem,

" means for setting intermediate limits of valve movement comprising means for setting intermediate limits for the range of valve movement,

means for setting the relative position of the range of valve movement between said upper and lower limits, and clutch controlled means remotely operable to selectively set the intermediate limits of valve movement and the range of valve movement between said upper and lower limits.

15. In a valve mechanism including a valve casing, a valve movable between upper and lower limits in said casing and a valve stem, means for setting intermediate limits of valve movement comprising means for setting intermediate limits for the range of valve movement, means for setting the relative position of the range ofvalve movement between said upper and lower limits, and control means, common to both of said means for selectively setting the intermediate limits of valve movement and the range of valve movement between said upper and lower limits. GERALD W. MCCULLOUGH. 

